{
   "containers": {
      "cna": {
         "providerMetadata": {
            "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038"
         },
         "descriptions": [
            {
               "lang": "en",
               "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix too early release of tcx_entry\n\nPedro Pinto and later independently also Hyunwoo Kim and Wongi Lee reported\nan issue that the tcx_entry can be released too early leading to a use\nafter free (UAF) when an active old-style ingress or clsact qdisc with a\nshared tc block is later replaced by another ingress or clsact instance.\n\nEssentially, the sequence to trigger the UAF (one example) can be as follows:\n\n  1. A network namespace is created\n  2. An ingress qdisc is created. This allocates a tcx_entry, and\n     &tcx_entry->miniq is stored in the qdisc's miniqp->p_miniq. At the\n     same time, a tcf block with index 1 is created.\n  3. chain0 is attached to the tcf block. chain0 must be connected to\n     the block linked to the ingress qdisc to later reach the function\n     tcf_chain0_head_change_cb_del() which triggers the UAF.\n  4. Create and graft a clsact qdisc. This causes the ingress qdisc\n     created in step 1 to be removed, thus freeing the previously linked\n     tcx_entry:\n\n     rtnetlink_rcv_msg()\n       => tc_modify_qdisc()\n         => qdisc_create()\n           => clsact_init() [a]\n         => qdisc_graft()\n           => qdisc_destroy()\n             => __qdisc_destroy()\n               => ingress_destroy() [b]\n                 => tcx_entry_free()\n                   => kfree_rcu() // tcx_entry freed\n\n  5. Finally, the network namespace is closed. This registers the\n     cleanup_net worker, and during the process of releasing the\n     remaining clsact qdisc, it accesses the tcx_entry that was\n     already freed in step 4, causing the UAF to occur:\n\n     cleanup_net()\n       => ops_exit_list()\n         => default_device_exit_batch()\n           => unregister_netdevice_many()\n             => unregister_netdevice_many_notify()\n               => dev_shutdown()\n                 => qdisc_put()\n                   => clsact_destroy() [c]\n                     => tcf_block_put_ext()\n                       => tcf_chain0_head_change_cb_del()\n                         => tcf_chain_head_change_item()\n                           => clsact_chain_head_change()\n                             => mini_qdisc_pair_swap() // UAF\n\nThere are also other variants, the gist is to add an ingress (or clsact)\nqdisc with a specific shared block, then to replace that qdisc, waiting\nfor the tcx_entry kfree_rcu() to be executed and subsequently accessing\nthe current active qdisc's miniq one way or another.\n\nThe correct fix is to turn the miniq_active boolean into a counter. What\ncan be observed, at step 2 above, the counter transitions from 0->1, at\nstep [a] from 1->2 (in order for the miniq object to remain active during\nthe replacement), then in [b] from 2->1 and finally [c] 1->0 with the\neventual release. The reference counter in general ranges from [0,2] and\nit does not need to be atomic since all access to the counter is protected\nby the rtnl mutex. With this in place, there is no longer a UAF happening\nand the tcx_entry is freed at the correct time."
            }
         ],
         "affected": [
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "unaffected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "include/net/tcx.h",
                  "net/sched/sch_ingress.c"
               ],
               "versions": [
                  {
                     "version": "e420bed02507",
                     "lessThan": "230bb13650b0",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "e420bed02507",
                     "lessThan": "f61ecf1bd5b5",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "e420bed02507",
                     "lessThan": "1cb6f0bae504",
                     "status": "affected",
                     "versionType": "git"
                  }
               ]
            },
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "affected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "include/net/tcx.h",
                  "net/sched/sch_ingress.c"
               ],
               "versions": [
                  {
                     "version": "6.6",
                     "status": "affected"
                  },
                  {
                     "version": "0",
                     "lessThan": "6.6",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.6.41",
                     "lessThanOrEqual": "6.6.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.9.10",
                     "lessThanOrEqual": "6.9.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "6.10",
                     "lessThanOrEqual": "*",
                     "status": "unaffected",
                     "versionType": "original_commit_for_fix"
                  }
               ]
            }
         ],
         "references": [
            {
               "url": "https://git.kernel.org/stable/c/230bb13650b0f186f540500fd5f5f7096a822a2a"
            },
            {
               "url": "https://git.kernel.org/stable/c/f61ecf1bd5b562ebfd7d430ccb31619857e80857"
            },
            {
               "url": "https://git.kernel.org/stable/c/1cb6f0bae50441f4b4b32a28315853b279c7404e"
            }
         ],
         "title": "bpf: Fix too early release of tcx_entry",
         "x_generator": {
            "engine": "bippy-c9c4e1df01b2"
         }
      }
   },
   "cveMetadata": {
      "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038",
      "cveID": "CVE-2024-41010",
      "requesterUserId": "gregkh@kernel.org",
      "serial": "1",
      "state": "PUBLISHED"
   },
   "dataType": "CVE_RECORD",
   "dataVersion": "5.0"
}